The digital currency has shot above the $15,000 mark for the first time -- the fourth big barrier it's broken in less than two days.

It had already zipped past $12,000, $13,000 and $14,000 within 24 hours before hitting $15,000 on Thursday morning in New York.

Despite a flurry of warnings from top economists and business leaders, its upward trajectory has continued -- albeit with a few sharp dips along the way.

After breaking above $11,000 last week, it abruptly plunged by more than $2,000 before resuming its climb. Buyer beware!

3. Brexit bites: British Prime Minister Theresa May is trying again to make progress on the Irish border, one of three key issues that must be addressed before negotiators can discuss trade terms with the EU.

May is racing to get a deal before a key EU summit next week.

But she is being hobbled by divisions within her own party, which remains at loggerheads over its plans for Brexit.

4. Media deal in court:AT&T(T) and the U.S. Department of Justice will be in court on Thursday.

The Justice Department filed a suit to block AT&T's bid to buy Time Warner(TWX), CNN's parent company, citing antitrust concerns. The first big question the judge needs to decide is when to schedule a trial. The two sides disagree when that should be.

The case could have implications for other big mergers, including CVS'(CVS) $69 billion acquisition of Aetna(AET).

5. Market overview:European markets were higher in early trade, but gains were limited to less than 1%. Asian markets were mixed, with Japan's Nikkei adding 1.5%.